New technologies that increase the safety of helmets

New technologies that increase the safety of helmets

The helmet falls from about one and a half meters in height. It descends very quickly along a guide that makes it crash precisely into an anvil with a rough surface, inclined at 45 degrees. The sharp and crisp noise of the impact comes after 5, maximum 10 milliseconds from the start of the test, echoing darkly in the MIPS laboratory in Täby, just north of Stockholm.

What we have just witnessed is the test number 57.540. Many have been carried out since the Swedish company, which specializes in creating systems that make helmets for riding, cycling, motorcycling and occupational protection safer, began research and development. Once again, the nine gyroscopes incorporated into the mannequin head that "wore" the helmet did their duty, recording all the forces at play at the moment of the collision.

The tip of the Iceberg It seems like a trivial test of resistance of the helmet, which on the other hand has split sharply at the point of impact, but underneath there is much more: on the one hand, because the test we have just witnessed does not only take into account the effects of a direct impact and linear (as usually happens when helmets are developed, designed to avoid fractures), but also and above all of the rotational movement, which in most cases is impressed during the impact. On the other hand, because the collected data will end up in the Virtual Test Lab (VLT), the virtual test laboratory in which the company has poured all its know-how, managing to create an extremely sophisticated and reliable digital simulation.

Thanks to it, today MIPS is able to perfectly replicate both the physical properties of the materials and structures of the helmets, as well as the complex dynamics of the impacts, which allows the Swedish company to do at least three different interesting things : carry out countless and reliable virtual tests, with savings for helmet manufacturers in terms of costs and environmental impact deriving from the production of prototypes; check "live" what happens to the helmet while the impact occurs, showing in detail, thanks to the simulation, how the materials react at each point during the impact (while usually limited to the analysis of the damage to the helmet ex-post) ; and then, more importantly, predict what effects each impact will have on the human brain.

The Multi-Directional Impact Protection System, capable of absorbing part of the rotational movement imparted to the helmet by an impact with an oblique surface.

Protect the brain. Really Yes, because it all began in the second half of the 90s, when the Swedish neurosurgeon Hans von Holst of Karolinska University Hospital, worried about the increase in brain damage caused by bicycle accidents, decides to study the relationship between brain injuries. and the construction of helmets. In over twenty years of academic research carried out together with Peter Halldin, a researcher at the Swedish Royal Institute of Technology and co-founder with von Holst of MIPS, he has thus developed a technology capable of better protecting the brain in the case of rotational movement, which it works by taking a cue from what already exists in nature. The brain, in fact, is naturally able to move about 10-15 millimeters in the skull to absorb a blow: in the same way, the Multi-Directional Impact Protection System (MIPS, in fact) is a sliding surface system (also this with an excursion of 10-15mm) designed to rotate inside the helmet in all directions, in such a way as to attenuate the amount of energy transferred to the head during an impact.

In a helmet equipped of this technology we therefore find three main components: the shell in expanded polystyrene (EPS), the low friction layer and, often between the two, a fastening system by means of elastomers. In an angled impact (which is also the most common but whose effects are neglected by current legislation), the fastening system by means of elastomers stretches to allow the EPS shell to rotate independently around the head.

“Today our technology has been chosen by 147 manufacturers, is present in 883 models and already equips 12.6 million helmets sold”, explains Daniel Lanner, Science Project Manager. He tells us the story of MIPS, of the choice to produce solutions for third parties (instead of directly producing helmets), so as to be able to spread their safety technology as much as possible. And then, again, of the struggle to stay on the market in the first 15 years of activity, almost twice bankruptcy, until the real success, which began in 2014 and which today translates into unstoppable growth. "Two years ago we were 43, today we are 90, and we grew up during the pandemic", proudly underlines Lanner.

The Virtual Test Lab During our visit to Täby, we also witnessed an absolute preview of a demo of the Virtual Test Lab. Created to speed up the development process and increase the reliability of new helmets, it uses mathematical models based on the Finite Element Method (FEM) to describe and apply the properties of helmets and their materials, but also especially those of the human brain. During the demo, we see the reconstruction of a helmet identical to that of the initial experiment appear on the screen: the foams that compose it, the coating and every other detail have been broken down into small polygons, each made up of 4 corners. To represent the reconstruction of this specific product, over 430 thousand are needed which, like as many pieces of an extraordinarily complex Lego, describe the object with extreme precision, drawing on a precious library of materials patiently built by MIPS.

A detail of the simulation that in the VLT describes the effects on the helmet of the impact on an oblique surface.

The "magic" of the simulation Just a few clicks, and in that helmet a head materializes, so we see it repeated in digital same test we had seen live at the beginning. We see the helmet breaking in the same way, in the same points, but this time we can slow down the blow, study it in detail as it happens, “dig” deep into the materials and see live deformation and breakage in otherwise inaccessible points. “What in 2018 required three months of development, thanks to these simulations today we can do it in 3 weeks - explains Marcus Arnesen, MIPS Model Development Engineer - and we are the only ones who can see what happens in the helmet. Usually a manufacturer has to develop up to 5 versions of a helmet before having the final one: if we do it like this, 2 or 3 are enough ".

When the human brain is added to the simulation, the demo becomes even more interesting: the more than two decades of MIPS research materialize in a mathematical model which, as for the helmet, describes the brain in all its parts, taking into account the properties of each part and "material", promptly showing the reactions and damage resulting from any impact. The purpose of the demo is to show the versatility of the Virtual Test Lab, but Isak Hampel Klang, the Computational Engineer responsible for this last session, also takes the opportunity to reaffirm the concept behind the success of MIPS: the simulated test on an oblique surface gives a strong rotation to the head, and the system shows much more serious consequences on the brain than a linear blow impressed with equal force. The same test, repeated by adding MIPS safety technology to the virtual helmet, highlights an important reduction in post-impact consequences.

Almost as if to say: “Did you see that we were right? ".

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